1. Field of the Invention
This invention relates to a measuring instrument wherein a movable member having a measuring element or the like is made movable relative to a workpiece to be measured rested on a bedplate, as in the two-dimensional measuring instrument, three-dimensional measuring instrument (coordinate measuring instrument), contour measuring instrument and strain measuring instrument or the like, and more particularly to improvement in a guide rail portions of the measuring instrument.
2. Description of the Prior Art
In general, in the above-described measuring instruments, a displacement of a measuring element has been detected as referenced from the upper surface of a bedplate, and hence, with the measuring instruments of the type, wherein only the measuring element is moved for measuring, it has been necessary to move a measuring element support member supporting the measuring element in parallel to the upper surface of the bedplate.
In view of the above, heretofore, guide rails finished with high accuracy have been directly affixed to the upper surface of the bedplate in parallel to each other by means of fittings for exclusive use and bolts. In consequence, there have been presented such disadvantages that a great amount of labor is needed for the installation of the guide rails, out of the area of the upper surface of the bedplate, an effective portion put to use for resting a workpiece is small, and a workpiece being heavy in weight cannot be parallelly moved from one side of the bedplate to be mounted thereon.
On the other hand, there are some cases where, for example, the guide rails are suspended from the ceiling of a house, or the guide rails are disposed on the ground through a bed in no connection with the bedplate. In this case, a great amount of labor is needed for obtaining parallelism between the upper surface of the bedplate and these guide rails, and moreover, anti-vibration measures for the guide rails must be taken, thus resulting in increased costs and lowered accuracy.
Further, in the above-described conventional constructions, since the guide rails are fixedly provided on the bedplate, there have been presented such disadvantages that, when the guide rails are to be replaced due to a damaged scale or the like, it is very troublesome to replace the guide rails with new ones, and the positioning of the guide rail is difficult, and hence, the maintenance of accuracy after the replacement is difficult. Further, in the conventional constructions, the positioning of the measuring element support member relative to the guide rails is difficult.